During the process of placing a paraffin embedded (also known as wax embedded biological specimens) biological specimen on microscope slides, (i.e., paraffin or wax embedded tissues section(s) and paraffin or wax embedded cytology specimen(s)), a time consuming step of drying the water trapped between the paraffin embedded section and the microscope slide as a result of the floatation of the paraffin section onto the microscope slide is typically carried out. This water is from the histological water floatation bath. The water from the process of floating the paraffin section(s) onto a histological water floatation bath and then picking up the section(s) with a microscope slide is the preferred method for placing a paraffin section onto a microscope slide. Another method in the art is the user will add water or other liquid (with or without chemicals present like adhesives) to the microscope slide and then place a paraffin section onto the water on the microscope slide. These prior art methods of liquid flotation or liquid mounting of a paraffin embedded biological specimen to a microscope slide are known here as “histological water,” “histological water flotation,” “histological water flotation bath,” “histological flotation water bath,” “water,” “liquid,” “liquid flotation,” “residual water,” “flotation water,” “flotation liquid,” and “mounted microscope slides.”
Since paraffin is hydrophobic and a water barrier, the trapped water between the paraffin section and the microscope slide must be removed so that the paraffin section can uniformly lay flat against the microscope slide and only then will the biological specimen become attached to the slide. This water trapped under the paraffin section and the residual water present on the microscope slide must be removed prior to placement of the slide, with paraffin section attached, in contact with aqueous and non-aqueous de-waxing solution to dissolve the paraffin therefore removing the paraffin in contact with the biological specimen prior to staining the biological specimen.
One method that has been used for removing the water trapped under a paraffin section and the paraffin surrounding the biological specimen on microscope slide, for a immunohistochemistry protocol, is letting the microscope slide and paraffin section dry at room temperature or under heat (i.e., air-dry, or 60° C. heated oven for 1 hour or 60° C. overnight) for 1 hour to overnight. This evaporation method (utilizing ambient room temperature air or a heat source) is excessively inefficient and excessively time consuming, and can produce tissue artifacts like crack artifacts in the tissue (due to uncontrolled evaporation of the water) and or bubble(s) artifact due to the heat inconsistently evaporating the water and a uncontrolled melting of the paraffin associated with the biological specimen. Ambient air evaporation of the water is very time consuming, in excess of 1 hour.
The evaporation method utilizing heat to evaporate the water and also melt the paraffin (excess of 55° C.) is also very time consuming, usually in the range of 30 minutes to 1 hour at 60° C. One would anticipate that if the water was exposed to increased heat, the evaporation time would decrease. This would be true, however, the increase in temperature (above 60° C.) produces unwanted heat artifacts and increases the problems associated with excessive heat evaporation. The method of evaporating the water present on and under the paraffin section and evaporating residual water on the microscope slide utilize only the inefficient method of evaporative drying or evaporative removal of the water. This method is based on excessive evaporation times (1 hour to overnight) for the water to evaporate, whether the evaporation is at ambient temperature (room temp) or evaporation is by heat which causes heat artifacts in the biological specimen.
Because the “drying” or “evaporation” of the water trapped under or associated with the paraffin section is uneven in all areas underneath the paraffin section or paraffin boarder surrounding the specimen (i.e., there are different areas and amounts of residual water under or around the tissue), during heating to evaporative the water, some melted paraffin areas can “float” on the evaporating water underneath itself, thus pulling pieces of delicate tissue away from the tissue specimen causing a detached tissue artifact. Another tissue artifact caused by heating the water on under the paraffin section can cause the water trapped under the paraffin section to go from a liquid phase to a gas phase and form a “gas bubble” under the tissue section which causes the delicate tissue to detach from the microscope slide and thus form a “bubble” or “rounded area” of missing tissue were the gas bubble was formed. These cracks, bubbles, and pulled away areas of the specimen are a significant staining artifact problem.
Since the drying of the water present around or under the paraffin section is not even and consistent do to the water being thicker or “pooled” in different areas around or under the paraffin section, there will be areas under the paraffin section and around the paraffin section that dry sooner than other areas around or under the paraffin section. The paraffin may start to melt while there is still water present under the paraffin. This melted paraffin will now be “floating” on the water underneath itself and can become mobile to “move” about the slide and away from its original mounted location. This movement of partial pieces of the once intact specimen can become important during the orientation of the original “whole” specimen that should have the same morphological size, shape, and physical characteristics of the embedded paraffin block that was cut by the microtome to make the paraffin section. These areas of “water-trapped floating specimen” on the microscope slide can be detrimental in the staining processes and in the interpretation of the specimen under a microscope since the original cut paraffin section no longer has the morphology of the paraffin embedded block or the originally cut biological specimen present in the paraffin block.
An accepted way to dry the water underneath a recently floated paraffin section onto a microscope slide is to dry the “wet” paraffin embedded section in a 60-100 degree Celsius oven with the microscope slide being placed most commonly in the vertical position in the oven for drying. This vertical positioning of the microscope slide cause the trapped water between the paraffin section and microscope slide to move from the top area of the paraffin section toward the bottom area of the paraffin section, which causes the “pooling effect” of the water under the paraffin section to increase at the lower end of the paraffin section due to the gravitational pull of the water towards the lower end of the paraffin section and thus increasing the likelihood of the delicate paraffin section's lower area to “detach,” “break away,” and/or “float” away from the upper paraffin section area.
This “water pooling” effect under the lower part of the paraffin section is significantly increased due to the physics of the trapped water under the paraffin section physically moving, due to gravity, toward the bottom of the paraffin section leading to the increased chance of the biological specimen “moving” or “breaking away” from the upper end of the paraffin section due to gravity pulling on the delicate paraffin section during this vertical drying. It is also known that drying a microscope slide in the horizontal position does not eliminate the “floating” or “pooling” effects of the water trapped under the paraffin embedded biological specimen, because the water is still trapped under the paraffin section. These unwanted heat induced problems and heat induced artifact(s), from heating, are only increased if the temperature is increased from the prior art evaporation temp of 60° C.
Another method known in the art of drying the floatation liquid from under or between a paraffin embedded section and a microscope slide is the use of “blotting” paper, or bibulous paper. The technician would, by hand or by manual method, “blot” the “wet” paraffin section directly with the bibulous paper. This “hands on” method has its draw backs related to the “tearing,” “ripping,” “dislodging,” “dislocating,” and otherwise damaging the delicate paraffin embedded biological specimen that is “floating” on the tissue floatation liquid between the paraffin embedded biological specimen and the microscope slide. This method is not repeatability reproducible due to the enormous manual labor intensive technical time to blot each and every microscope slide in a plurality of microscope sides. The different pressures and forces exceeded onto the delicate paraffin embedded biological specimen from each hand, finger, or otherwise manually pressing or touching of the bibulous paper is significant enough to damage the paraffin embedded biological specimen.
The paraffin embedded biological specimen would be damaged in part by the dry bibulous paper touching the wet paraffin embedded biological specimen, with the possibility of the wet paraffin embedded biological specimen “sticking” to the dry bibulous paper and possibly pulling up the paraffin embedded biological specimen and adhering at least part of the paraffin embedded biological specimen to the dry bibulous paper. This method is not effective or efficient, not to mention, the added cost of another consumable needed to be purchased to remove the floatation liquid from a wet paraffin embedded biological specimen. One would anticipate that to save the cost of the bibulous and the time to blot each microscope slide, it would be advantageous to keep with the prevailing method of heating the wet microscope slide and wet paraffin embedded biological specimen attached in a heating oven. It is common prior art practice after “blotting” to still place the “blotted” microscope slide and paraffin embedded biological specimen into a conventional heating oven to evaporate the residual floatation liquid that is still present between the paraffin embedded biological specimen and the microscope slide after “blotting.”
To this end, a need exists for an apparatus and method for efficiently and effectively removing floatation liquid from between a microscope slide and a paraffin embedded biological specimen. It is to such an apparatus and method that the inventive concepts disclosed herein are directed.